For the purpose of heating a floor it is known to manually lay a flexible plastic pipe in the floor plaster, whereby one end of the pipe is connected to the outgoing part and its other end is connected to the return part of a hot water line or pipe. The laying of such a plastic pipe must be carried out with particular care, in order to obtain a satisfactory heating of the floor. However, it is not possible to reliably obtain an absolutely uniform heating of the floor, because the flexible plastic hose can be displaced during manual laying. In addition, the hose must have a diameter of at least 10 mm to permit its laying by hand. Laying the hose also takes time. In addition, the efficiency of this floor heating is unsatisfactory, because the temperature of the outgoing part of the hot water must be much higher than the sought ambient temperature.
DE-OS No. 31 24 048 discloses a heater for a hot water surface heating system, particularly for floor or wall heating purposes, in which the hot water is passed through at least one plastic pipe laid in one plane in the floor or wall part to be heated and connected to the outgoing and return parts. The heater comprises a plurality of reciprocally spaced, small diameter, flexible plastic pipes combined to form a mat and which are combined at least at one end to form connections for the connecting pieces forming the outgoing and return parts for the hot water receiving the pipe ends in parallel arrangement and accompanied by reciprocal sealing. The mat is reinforced by retaining members fixing the pipe spacings and arranged on the circumference thereof and at right angles to the pipes and in this way form a flexible network-type unit which can be freely laid in the plaster of a floor or embedded in the plaster of a wall. Laying in the floor plaster takes place in such a way that the mat formed from the plastic pipes is placed on a substrate and connected to the heating system, so that an adequate pressure can be produced in the plastic pipes. Subsequently the mat is fixed to the substrate and then the plaster is applied. In this process, the plastic pipes are consequently connected to the underside of the set or hardened plaster, because the fixing of the mat to the substrate prevents an uncontrolled mat floating in the still not set plaster. Such an uncontrolled floating could lead to there being no adequate covering by the plaster of the plastic pipes.
In another known process relatively large diameter individual plastic pipes are laid on the substrate and anchored in the insulation before the plaster is applied thereto. Thus, the plastic pipes are located below the hardened plaster layer, which has a thickness of approximately 30 mm. The thus produced floor heating system requires relatively high temperatures of the heating medium conveyed through the plastic pipes and also leads to a non-uniform heat distribution in the floor. In addition, there is only a limited controlability of heating.